This invention relates generally to thermoplastic articles of manufacture and methods and apparatus for making the same. The present invention relates more particularly, but not by way of limitation, to such an article of manufacture made of poly(arylene sulfide) with multiple integral sections of different cross-sectional shapes and to methods and apparatus for making the same in a pultrusion process.
A thermoplastic material, such as poly(arylene sulfide), is characterized by its ability to be heated or reheated, molded and cooled into a hardened state. During this process, it can be combined with a reinforcing material, such as one or more fiber strands, whereby the manufactured article is a reinforced thermoplastic composite which can be used in place of other materials, such as steel, wood or aluminum which may have inferior qualities to the reinforced thermoplastic composite.
One method of making such a composite is referred to as "pultrusion". For example, a strand of glass fibers is pulled through a source of thermoplastic material to impregnate and surround the strand of fibers with the thermoplastic material. The resultant composite is pulled through a heating, molding and cooling sequence to form a hardened article. For example, this can be a finished article ready for some end usage (such as a sucker rod used in pumping oil from an oil well) or it can be an article which is to be further used in producing a finished article.
Heretofore, there have been disclosures about forming such articles with variable cross-sectional areas. I am not aware, however, of disclosures about any such articles, or the methods and apparatus for making them, where the articles have different cross-sectional shapes integrally formed in a continuous process. Satisfying such void would provide a product which would have multiple, selected integral shapes and it would provide an efficient technique for producing it.